average word length

[micseydel]

Shouldn't it be

You're right

Output:
$ python
Python 2.7.15 (default, May  1 2018, 16:44:08) 
[GCC 4.2.1 Compatible Apple LLVM 9.1.0 (clang-902.0.39.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from string import letters
>>> letters
'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
>>> 
$ python3
Python 3.6.5 (v3.6.5:f59c0932b4, Mar 28 2018, 03:03:55) 
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from string import letters
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: cannot import name 'letters'
>>> from string import ascii_letters
>>> 

Thanks for the catch :)